Low-complexity intra prediction for video coding

1. A video encoding method comprising computer executable steps executed by a processor of a video encoder to implement an intra-prediction operation that derives a prediction block of a target block with boundary pixels of the target block interpolated along an intra prediction angle, wherein the boundary pixels comprise a horizontal array of horizontal boundary pixels and a vertical array of vertical boundary pixels, the intra-prediction operation comprising: obtaining a value of an inverse angle parameter, corresponding to the intra prediction angle, from a look-up table which lists values of inverse angle parameters in relation, respectively, to a plurality of different intra prediction angles; identifying at least some of the vertical boundary pixels located in the vertical array at positions which are a function of multiplication between the obtained value of the inverse angle parameter and a value of a horizontal location identifier which is a variable representing positions in an extension of an extended horizontal array; adding the identified at least some of the vertical boundary pixels as horizontal boundary pixels to the extension of the extended horizontal array; and using only the horizontal boundary pixels in the extended horizontal array, without using the vertical boundary pixels, to derive the prediction block of the target block.

2. A video decoding method comprising computer executable steps executed by a processor of a video decoder to implement an intra-prediction operation that derives a prediction block of a target block with boundary pixels of the target block interpolated along an intra prediction angle, wherein the boundary pixels comprise a horizontal array of horizontal boundary pixels and a vertical array of vertical boundary pixels, the intra-prediction operation comprises: obtaining a value of an inverse angle parameter, corresponding to the intra prediction angle, from a look-up table which lists values of inverse angle parameters in relation, respectively, to a plurality of different intra prediction angles; identifying at least some of the vertical boundary pixels located in the vertical array at positions which are a function of multiplication between the obtained value of the inverse angle parameter and a value of a horizontal location identifier which is a variable representing positions in an extension of an extended horizontal array; adding the identified at least some of the vertical boundary pixels as horizontal boundary pixels to the extension of the extended horizontal array; and using only the horizontal boundary pixels in the extended horizontal array, without using the vertical boundary pixels, to derive the prediction block of the target block.

3. A video encoder comprising a processor of a computer system and a memory that stores programs executable by the processor to implement an intra-prediction operation that derives a prediction block of a target block with boundary pixels of the target block interpolated along an intra prediction angle, wherein the boundary pixels comprise a horizontal array of horizontal boundary pixels and a vertical array of vertical boundary pixels, the intra-prediction operation implemented by the processor to: obtain a value of an inverse angle parameter, corresponding to the intra predication angle, from a look-up table which lists values of inverse angle parameters in relation, respectively, to a plurality of different intra prediction angles; identify at least some of one of the vertical boundary pixels located in the vertical array at positions which are a function of multiplication between the obtained value of the inverse angle parameter and a value of a horizontal location identifier which is a variable representing positions in an extension of an extended horizontal array; add the identified at least some of the vertical boundary pixels as horizontal boundary pixels to the extension of the extended horizontal array; and use only the horizontal boundary pixels in the extended horizontal array, without using the vertical boundary pixels, to derive the prediction block of the target block.

4. A video decoder comprising a processor of a computer system and a memory that stores programs executable by the processor to implement an intra-prediction operation that derives a prediction block of a target block with boundary pixels of the target block interpolated along an intra prediction angle, wherein the boundary pixels comprise a horizontal array of horizontal boundary pixels and a vertical array of vertical boundary pixels, the intra-prediction operation implemented by the processor to: obtain a value of an inverse angle parameter, corresponding to the ultra predicition angle, from a look-up table which lists values of inverse angle parameters in relation, respectively, to a plurality of different intra prediction angles; identify at least some of the vertical boundary pixels located in the vertical array at positions which are a function of multiplication between the obtained value of the inverse angle parameter and a value of a horizontal location identifier which is a variable representing positions in an extension of an extended horizontal array; add the identified at least some of the vertical pixels as horizontal boundary pixels to the extension of the extended horizontal array; and using only the horizontal boundary pixels in the extended horizontal array, without using the vertical boundary pixels, to derive the prediction block of the target block.